1. The effect of dietary flax oil on growth rate, blood haemoglobin content, mortality and incidence of pulmonary hypertension and ascites in broilers at ambient pressure and at reduced atmospheric pressure was examined. 2. Birds were housed either in hypobaric chambers simulating 1000, 1500 or 2200 m altitude or in pens at ambient atmospheric pressure and fed on diets containing 100 g/kg added fat as either an animal/vegetable (A/V) blend or flax oil. 3. Birds raised under hypobaric conditions had a decreased growth rate and increased mortality, blood haemoglobin content, and incidence of pulmonary hypertension and ascites compared to the groups at normal atmospheric pressure. 4. Broilers fed on the diet containing flax oil showed no difference in growth rate or blood haemoglobin content compared to birds fed on the A/V fat diet raised at the same altitude. 5. Inclusion of flax oil in the diet decreased mortality and the incidence of ascites at 2200 m and pulmonary hypertension at 1500 m. 6. Flax oil may be an effective method of reducing ascites and pulmonary hypertension in broilers without affecting performance.

Two trials were conducted with a total of 12 beef heifers and steers to determine the effect of 48-hr deprivation of feed or water or both on rectal temperature, respiratory and heart rates, electrocardiograph (EKG) patterns, packed cell volume (PCV) and the concentrations of serum sodium, potassium, calcium and magnesium. The same measurements plus the serum concentration of total acid-soluble phosphorus were made in a third trial with six steers and a 96-hr deprivation period. A fourth trial was conducted with three rumen fistulated steers to determine the effect of manually emptying the rumen on EKG patterns, Deprivation of feed or water or both for 96 hr reduced (P<.05) rectal temperature by 1.5% and respiratory rate by 47% and increased (P<.05) P and R EKG amplitudes by 33% and 35%, respectively, PCB by 21% and serum phosphorus by 43%. Deprivation reduced heart rate 19% and increased serum sodium and potassium 12 and 23%, respectively, but these changes were not significant. These changes appeared smaller and less consistent for animals deprived for 48 hours. The physiological changes associated with both 48-hr and 96-hr deprivation were most pronounced during the deprivation period and for 24 hr after reintroduction of feed and water with little evidence of treatment effects 48 hr after the reintroduction of feed and water. For animals deprived 96 hr, changes in respiratory rate (P<.01), PCV (P~.05) and serum phosphorus (P<.05) were greater for the animals fed concentrate than for those fed in obtaining the physiological measurements in these trials.forage; changes in heart rate and the P-R and T-P EKG intervals tended to be greater for the animals deprived of both feed and water than for animals deprived of feed or water alone. Manually emptying the rumen had little effect on EKG patterns. In the absence of engorgement after a deprivation period as long as 96 hr, the measurements in this study indicated that beef cattle return quickly to a physiologically normal state. (

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